The use of certain industrial solvents has curtailed in recent years due, in part, to concerns over their impact on the environment and their effects on general health and safety. This is especially true of solvents known to have a high volatile organic content (VOC), as such compounds may contribute to greenhouse gas production and ozone depletion. In some instances, traditional high VOC solvents can also be carcinogenic, teratogenic, toxic, and/or mutagenic. Therefore, a number of common solvents have come under increased regulatory scrutiny and therefore suffer from decreased use. Such solvents include aromatics (e.g., benzene, toluene, xylenes, and the like), ketones (e.g., methyl ethyl ketone, methyl isobutyl ketone, and the like), halogenated organics (e.g., dichloromethane, perchloroethylene, and the like), glycol ethers, and alcohols (e.g., methanol, isopropanol, ethylene glycol, and the like).
Certain derivatives of renewable feedstocks can provide more suitable alternatives to high VOC solvents. For example, fatty acid alkyl esters (e.g., from the transesterification of vegetable oils, animal fats, or other lipids) can provide environmentally friendly alternatives to traditional oxygenated solvents. Methyl soyate, for example, has a low VOC value, a high flash point, a low toxicity, and a high biodegradability. Terpene oils from citrus and pine (d-limonene and pinene, respectively) may also serve as suitable alternatives to certain traditional organic solvents.
Such renewable solvents are not without their problems, however. For example, d-limonene and dipentene (a racemate of d-limonene) are acute and chronic aquatic toxins, and also have an irritating and sensitizing effect on the skin. Further, d-limonene is highly inflammable (e.g., more so than petroleum distillates) and can be subject to fluctuations in supply and price. Fatty acid alkyl esters can overcome some of these deficiencies of terpene oils, but can also exhibit poor solvency relative to certain incumbents.
Thus, there is a continuing need to develop solvent compounds and compositions that are renewably sourced, exhibit high solvency, and have a desirable health and safety profile.